CN110474556B - Inverter control method - Google Patents

Inverter control method Download PDF

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Publication number
CN110474556B
CN110474556B CN201910156518.7A CN201910156518A CN110474556B CN 110474556 B CN110474556 B CN 110474556B CN 201910156518 A CN201910156518 A CN 201910156518A CN 110474556 B CN110474556 B CN 110474556B
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output frequency
voltage
link voltage
load
inverter
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CN110474556A (en
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裵埰奉
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LS Electric Co Ltd
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LSIS Co Ltd
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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/66—Regulating electric power
    • G05F1/67—Regulating electric power to the maximum power available from a generator, e.g. from solar cell
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B17/00—Pumps characterised by combination with, or adaptation to, specific driving engines or motors
    • F04B17/006—Solar operated
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
    • F04B49/00—Control, e.g. of pump delivery, or pump pressure of, or safety measures for, machines, pumps, or pumping installations, not otherwise provided for, or of interest apart from, groups F04B1/00 - F04B47/00
    • F04B49/06—Control using electricity
    • F04B49/065—Control using electricity and making use of computers
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D13/00—Pumping installations or systems
    • F04D13/02—Units comprising pumps and their driving means
    • F04D13/06—Units comprising pumps and their driving means the pump being electrically driven
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
    • G01R19/16528—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values using digital techniques or performing arithmetic operations
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/32—Means for protecting converters other than automatic disconnection
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
    • H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
    • H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
    • H02P27/085—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02S—GENERATION OF ELECTRIC POWER BY CONVERSION OF INFRARED RADIATION, VISIBLE LIGHT OR ULTRAVIOLET LIGHT, e.g. USING PHOTOVOLTAIC [PV] MODULES
    • H02S40/00—Components or accessories in combination with PV modules, not provided for in groups H02S10/00 - H02S30/00
    • H02S40/30—Electrical components
    • H02S40/32—Electrical components comprising DC/AC inverter means associated with the PV module itself, e.g. AC modules
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2201/00—Apparatus for treatment of water, waste water or sewage
    • C02F2201/009—Apparatus with independent power supply, e.g. solar cells, windpower, fuel cells
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
    • H02M1/4208—Arrangements for improving power factor of AC input
    • H02M1/425—Arrangements for improving power factor of AC input using a single converter stage both for correction of AC input power factor and generation of a high frequency AC output voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • H02M7/53875—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current with analogue control of three-phase output
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/56—Power conversion systems, e.g. maximum power point trackers

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Sustainable Energy (AREA)
  • General Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Automation & Control Theory (AREA)
  • Computer Hardware Design (AREA)
  • Inverter Devices (AREA)
  • Control Of Electrical Variables (AREA)
  • Supply And Distribution Of Alternating Current (AREA)

Abstract

A method of controlling an inverter in a solar pump system is disclosed. In the method of an embodiment of the present invention, when the dc link voltage is greater than or equal to the reference level and the output frequency of the ac voltage applied to the load is increased in the previous cycle, the output frequency of the ac voltage to be applied to the load is increased with a first slope, and when the dc link voltage is greater than or equal to the reference level and the output frequency of the ac voltage applied to the load is decreased in the previous cycle, the output frequency of the ac voltage to be applied to the load is increased with a second slope smaller than the first slope.

Description

Inverter control method
Technical Field
The invention relates to an inverter control method.
Background
A solar pump (solar pump) is a device that uses energy generated from a solar module and drives a pump through an inverter to generate and supply fresh water. The solar pump system is an apparatus capable of supplying water channels and electricity most effectively, is used for various purposes such as drinking water, agricultural water, seawater desalination and the like in areas where water channel network infrastructure is scarce, can supply groundwater by suction without additional energy supply in remote areas where power supply is difficult, and is evaluated as an optimum system capable of solving the shortage of water channels and electricity in remote areas. The indian government has mandated the installation of 50,000 solar pumps for irrigation and drinking water supply in 2014, and is also currently in extended installations.
Fig. 1 is a structural diagram of a conventional solar pump system including a solar module 100, an inverter 200, and a control unit 300.
As described above, one of important control methods in a solar pump system that generates electricity using solar energy is Maximum Power Point Tracking (MPPT) control. The solar inverter always generates maximum power through MPPT control that tracks the maximum power generation point of the solar cell.
The conventional MPPT control method, the hill climbing method, which is the most basic control method among MPPT control methods, is a method of changing a duty ratio (duty) by a predetermined displacement to find a maximum power point, and although control is easy and simple, there is a problem that the estimation of the maximum power point is slow when the solar radiation amount abruptly changes.
Among conventional MPPT control methods, a perturbation and observation method is the most common MPPT control method, and is a method of operating at the maximum power point by measuring a change in power with an increase or decrease in voltage. However, this method has a problem that the control characteristics deteriorate when the light amount is low.
Further, in the conventional MPPT control method, the impedance matching method is to maximize the output of the solar cell by using a point at which the impedance of the load and the impedance of the solar cell become the same, and the method is excellent in tracking performance, but has a problem that it is slightly complicated and requires a large amount of calculation.
As described above, in the existing solar pump system as shown in fig. 1 using the MPPT control method of the existing various solar pump systems, in order to control the voltage applied to the water pump 400, the control unit 300 uses the dc link voltage and the output current of the inverter unit 52 as information for generating the PWM output waveform of the inverter 200 and detecting the low voltage/overvoltage. That is, the voltage sensor 210 supplies the dc link voltage of the inverter 200 to the control unit 300, and the current sensor 220 supplies the output current of the inverter 200 to the control unit 300, thereby generating the PWM output waveform.
However, a rapid increase in the dc link voltage may cause an overvoltage problem, a rapid decrease in the dc link voltage may cause a low voltage problem, and the water pump 400 may not be operated in a low voltage and high voltage state. Frequent changes in the stop or operating state of the water pump 400 may cause malfunction of the water pump 400 as in the case of frequent and rapid changes in frequency, so that a large amount of energy loss may occur.
In addition, since the variable frequency output of the PWM method of inverter 200 is detected instead of the input power of inverter 200 in the conventional case, there is a problem in that the calculation accuracy of the output power is lowered and the stress of water pump 400 is increased due to the pulsation of the output frequency.
That is, as described above, since the control unit 300 detects the voltage and the output current of each node of the inverter 200 to perform the MPPT control, it is necessary to accurately detect the voltage and the current, and there is a problem that the higher the required accuracy is, the more expensive the sensor disposed in the system is.
Disclosure of Invention
An object of the present invention is to provide an inverter control method capable of preventing an increase in stress due to pulsation of an output frequency by tracking a maximum power point using a dc link voltage of an inverter.
In order to solve the technical problem described above, in a system for converting power applied from a solar module and applying the converted power to a load, an inverter control method according to an embodiment of the present invention may include: a step of receiving a dc link voltage of the inverter; a step of increasing an output frequency of the alternating-current voltage to be applied to the load with a first slope when the direct-current link voltage is above a reference level and the output frequency of the alternating-current voltage to be applied to the load increases in a previous cycle; and a step of increasing the output frequency of the alternating voltage to be applied to the load with a second slope smaller than the first slope when the direct-current link voltage is above a reference level and the output frequency of the alternating voltage to be applied to the load decreases in a previous cycle.
The inverter control method according to an embodiment of the present invention may further include: a step of reducing an output frequency of the alternating voltage to be applied to the load when the direct-current link voltage is less than a reference level and the direct-current link voltage is less than the reference level in a previous cycle.
The inverter control method according to an embodiment of the present invention may further include: a step of storing an output frequency in a current cycle (storing the output frequency) and reducing the output frequency of the alternating voltage to be applied to the load when the direct-current link voltage is less than a reference level and the direct-current link voltage is above the reference level in a previous cycle.
The inverter control method according to an embodiment of the present invention may further include: a step of fixing the output frequency of the alternating voltage applied to the load when the output frequency is greater than the stored output frequency after increasing the output frequency of the alternating voltage to be applied to the load with the second slope.
The inverter control method according to an embodiment of the present invention may further include: and clearing the output frequency state and clearing the stored output frequency when the direct current link voltage is stable in a preset time after the output frequency is fixed.
In an embodiment of the present invention, whether the dc link voltage is stable may be determined according to whether the dc link voltage varies within a critical range.
According to the present invention as described above, it is possible to sense a change in the dc link voltage without an additional sensor, thereby making it possible to maximally utilize the power generation energy of the solar module.
Drawings
Fig. 1 is a structural view of a conventional solar pump system.
Fig. 2 is a block diagram for schematically illustrating a solar pump system to which an embodiment of the present invention is applied.
Fig. 3 is a flowchart for explaining an inverter control method according to an embodiment of the present invention.
Description of the reference numerals
1: control unit
2: solar module
3: EMC filter
4: fuse wire
5: inverter with a voltage regulator
50: boost converter
51: DC link capacitor
52: inverter unit
53: voltage sensor
6: water pump
7: water tank
Detailed Description
In order that the structure and effects of the present invention can be fully understood, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described below, but may be implemented in various forms and may be variously changed. However, the description of the present embodiments is intended to provide a complete disclosure of the present invention and to fully disclose the scope of the present invention to those of ordinary skill in the art to which the present invention pertains. In the drawings, the size of constituent elements is exaggerated and the scale of constituent elements may be exaggerated or reduced for convenience of explanation.
The terms "first", "second", and the like may be used to describe various constituent elements, but these constituent elements should not be limited to the above terms. The above terms may be used only to distinguish one constituent element from another constituent element. For example, a "first constituent element" may be named a "second constituent element", and similarly, a "second constituent element" may also be named a "first constituent element", without departing from the scope of the present invention. Furthermore, unless the context clearly dictates otherwise, expressions in the singular include a plurality of expressions. Terms used in the embodiments of the present invention may be construed as well known to those skilled in the art, unless otherwise defined.
Next, an inverter control method according to an embodiment of the present invention will be described with reference to fig. 2 and 3.
Fig. 2 is a block diagram for schematically illustrating a solar pump system to which an embodiment of the present invention is applied.
As shown in the drawing, a solar pump system to which an embodiment of the present invention is applied may include a solar module 2, an Electromagnetic Compatibility (EMC) filter 3, a fuse (fuse)4, an inverter 5, a control unit 1, a water pump 6, and a water tank 7. However, in an embodiment of the present invention, the water pump 6 is exemplified as the load of the inverter 5, but the present invention is not limited thereto, and various loads that can receive the energy generated by the solar module 2 through the inverter 5 may be applicable.
In addition, the inverter 5 may include a boost converter 50, a dc link capacitor 51, an inverter unit 52, and a voltage sensor 53.
The solar module 2 is formed by connecting and coupling solar cells in the vertical and horizontal directions, and the electricity generated by the solar cells is collected at the same time in the module to generate electric power.
The EMC filter 3 can minimize electromagnetic interference generated in the power applied from the solar module 2 and prevent damage due to the above electromagnetic interference, and the fuse 4 can be cut off when an excessive current flows into the inverter 5. However, the EMC filter 3 and the fuse 4 are exemplary, and various constituent elements for eliminating noise generated in the electric power flowing in from the solar module 2 may be used in the solar pump system according to an embodiment of the present invention.
As described above, the dc voltage from which noise is removed by the EMC filter 3 and the fuse 4 may be applied to the inverter 5, and the dc voltage applied to the inverter 5 may be boosted by the boost converter 50 and stored in the dc link capacitor 51. The control unit 1 of an embodiment of the present invention may supply, to the inverter unit 52, a switching signal for controlling the switching operation of the plurality of switching elements of the inverter unit 52 of the inverter 5 with reference to the dc link voltage detected by the voltage sensor 53. That is, the output frequency of the inverter unit 52 of the inverter 5 may be determined under the control of the control unit 1, which will be described in detail below.
The change in the dc link voltage of the inverter 5 varies according to the amount of solar radiation, and the amount of voltage change decreases when the dc link voltage is sufficient, and may become large when the dc link voltage is insufficient.
The water pump 6 is driven by the ac voltage output from the inverter unit 52 of the inverter 5, and water drawn by the water pump 6 may be stored in the water tank 7. The water transferred to the water tank 7 may be used as drinking water, industrial water, agricultural water, livestock water, etc.
In the conventional case, tracking the maximum power point using the inverter output current may cause an increase in system stress due to rapid pulsation of the output frequency, but in an embodiment of the present invention, the increase in system stress due to pulsation of the output frequency can be prevented by tracking the maximum power using only the dc link voltage of the inverter without an additional sensor.
That is, the control unit 1 according to an embodiment of the present invention can prevent the dc link voltage from decreasing by increasing the output frequency of the inverter 2 when the dc link voltage is equal to or higher than the predetermined reference level and decreasing the output frequency again when the output frequency is higher than the power generation energy of the solar module 1 and the dc link voltage is lower than the reference level.
Further, even if the dc link voltage becomes sufficient again after the output frequency is lowered, the output frequency is not immediately raised, but the stability of the dc link voltage is determined after the output frequency is stably raised to a point at which the dc link voltage becomes insufficient, and when it is determined that the dc link voltage is stable, the normal acceleration operation is performed. The detailed operation of the control unit 1 will be described below with reference to the drawings.
Fig. 3 is a flowchart for explaining an inverter control method according to an embodiment of the present invention.
As shown, in the system of an embodiment of the present invention, the control unit 1 may periodically receive the dc link voltage from the voltage sensor 53 (S41), and may confirm whether the received dc link voltage is equal to or greater than or less than a reference level (S42).
If the determination result of S42 indicates that the dc-link voltage in the current cycle is less than the reference level, it may be confirmed again whether the dc-link voltage in the previous cycle is greater than or equal to or less than the reference level (S43).
If the determination result of S43 indicates that the dc-link voltage in the previous cycle is equal to or greater than the reference level, that is, if the dc-link voltage in the current cycle decreases for the first time to become less than the reference level, the output frequency in the current cycle may be stored as the first output frequency (S44), and returned after decreasing the output frequency (S45).
Decreasing the output frequency means that the amount corresponding to the set decreasing slope may be decreased discontinuously (discrete) or continuously (continuous). That is, the output frequency may be continuously decreased for a predetermined time in accordance with the setting at a set slope, or may be decreased by decreasing the output frequency in the previous cycle by a discrete value corresponding to the slope set.
However, if the determination result of S43 indicates that the dc link voltage in the previous cycle is less than the reference level, i.e., if the dc link voltage in the current cycle does not become less than the reference level for the first time, S45 may be entered to decrease the output frequency.
The control unit 1 controls on/off of the switching elements by transmitting the PWM signal to gates of the plurality of switching elements of the inverter unit 52 of the inverter 5, so that the inverter unit 52 outputs the alternating current. That is, if the control unit 1 decreases the output frequency, the output frequency of the alternating current synthesized by the inverter unit 52 decreases, so that the output frequency of the alternating current output from the inverter unit 52 decreases to slow down the driving speed of the water pump 6.
On the other hand, if the determination result of S42 indicates that the dc link voltage in the current cycle is equal to or greater than the reference level, the control unit 1 may confirm whether the output frequency has decreased in the previous cycle (S46).
If the determination result of S46 indicates that the output frequency has not decreased in the previous cycle, that is, if the dc link voltage is also greater than the reference level in the previous cycle, the control unit 1 may return after increasing the output frequency at a frequency corresponding to the first slope (S47).
Increasing the output frequency means that the output frequency of the alternating current synthesized by the switching elements of the inverter unit 52 increases to increase the driving speed of the water pump 6. Further, increasing the output frequency with the first slope means that the amount corresponding to the first slope may be increased discontinuously or continuously. That is, the output frequency may be continuously increased for a predetermined time in accordance with the first slope according to the setting, or a discrete value corresponding to the first slope may be added to the output frequency in the previous cycle to increase the output frequency.
However, if the determination result of S46 indicates that the output frequency decreased in the previous cycle, that is, if the dc link voltage becomes sufficient again from insufficient, the output frequency may be increased with a second slope smaller than the first slope of S47 (S48).
Thereafter, the control unit 1 confirms whether the output frequency increased with the second slope is equal to or greater than the first output frequency stored in S44 (S49), and fixes the output frequency if the output frequency is equal to or greater than the first output frequency (S50). And returning if the output frequency is less than the first output frequency.
After fixing the output frequency, the control unit 1 may determine whether the dc link voltage is stable for a predetermined time (S51). Determining whether the dc link voltage is stable may first determine a critical range of magnitude of the dc link voltage variation, determine that the dc link voltage is unstable if the variation of the dc link voltage exceeds the critical range for a predetermined time, and determine that the dc link voltage is stable if the variation of the dc link voltage is within the critical range. The variation threshold range of the dc link voltage as described above may be previously stored by the control unit 1 according to the setting. In order to store the first output frequency and the critical range, the control unit 1 may further include a memory.
Thereafter, if the determination result of S51 indicates that the dc link voltage is stable for a predetermined time, control unit 1 may clear the state. That is, the output frequency lowering state may be cleared, and the stored first output frequency is cleared.
As described above, according to the inverter control method of an embodiment of the present invention, when the dc link voltage becomes sufficient again after the output frequency is lowered due to the shortage of the dc link voltage, the output frequency is not increased immediately, but the output frequency (first output frequency) up to the time point when the dc link voltage becomes insufficient is stably increased (slope is small), then the stability of the dc link voltage is determined for a predetermined time period, and after the stability is determined, the normal run-up (slope is large) is performed.
In an embodiment of the present invention, the frequent change of the frequency of the water pump 6 causes a malfunction, and therefore, the output frequency is increased when the dc link voltage is in a sufficient state (above the reference level), and the output frequency is decreased when the dc link voltage is in an insufficient state (below the reference level) to prevent the dc link voltage from further decreasing, thereby making it possible to maximally utilize the energy generated by the solar module 2 without causing a low voltage problem.
In this case, in order to prevent a variation in output frequency that may occur due to a variation in dc link voltage depending on weather conditions or illuminance, when the dc link voltage changes from the insufficient state to the sufficient state, the output frequency may be increased with a slope that is smaller than that in the sufficient state. In addition, it is possible to store the corresponding output frequency when changing from the sufficient state to the insufficient state, fix the output frequency when the output frequency increased with a small slope is larger than the stored output frequency, determine the stability of the dc link voltage, and increase the output frequency again when it is determined that the dc link voltage is stable.
The rapid increase of the dc link voltage causes an overvoltage, and the rapid decrease of the dc link voltage causes a low voltage, under which the water pump 6 cannot be operated. In addition, frequent changes in the operating/stopping state of the pump 6 may cause malfunction of the pump 6 as in the case of frequent changes, thereby increasing energy loss.
In the past, the dc link voltage was used as information for generating a PWM output waveform for controlling the water pump 6 and detecting a low voltage/overvoltage, but in an embodiment of the present invention, the increase and decrease of the dc link voltage was continuously confirmed, thereby changing the output frequency to prevent the dc link voltage from rapidly changing according to the amount of insolation.
According to the present invention as described above, it is possible to sense a change in the dc link voltage without an additional sensor, thereby making it possible to maximally utilize the power generation energy of the solar module.
It is to be understood that the embodiments according to the present invention described above are merely exemplary, and those skilled in the art can embody various modifications and equivalent embodiments. Therefore, the true technical scope of the present invention should be determined by the claims.

Claims (5)

1. An inverter control method employed in a system for converting power applied from a solar module and applying it to a load, wherein the inverter control method comprises:
a step of receiving a dc link voltage of the inverter;
a step of increasing an output frequency of the alternating-current voltage to be applied to the load with a first slope when the direct-current link voltage is above a reference level and the output frequency of the alternating-current voltage to be applied to the load increases in a previous cycle;
a step of increasing the output frequency of the alternating-current voltage to be applied to the load with a second slope smaller than the first slope when the direct-current link voltage is above a reference level and the output frequency of the alternating-current voltage to be applied to the load decreases in a previous period; and
a step of reducing an output frequency of the alternating voltage to be applied to the load when the direct-current link voltage is less than a reference level and the direct-current link voltage is less than the reference level in a previous cycle.
2. The inverter control method according to claim 1, further comprising:
storing the output frequency in the current cycle as a step of storing the output frequency and reducing the output frequency of the alternating voltage to be applied to the load when the direct-current link voltage is less than the reference level and the direct-current link voltage is above the reference level in the previous cycle.
3. The inverter control method according to claim 2, further comprising:
a step of fixing the output frequency of the alternating voltage applied to the load when the output frequency is greater than the stored output frequency after increasing the output frequency of the alternating voltage to be applied to the load with the second slope.
4. The inverter control method according to claim 3, further comprising:
and clearing the output frequency state and clearing the stored output frequency when the direct current link voltage is stable in a preset time after the output frequency is fixed.
5. The inverter control method according to claim 4,
whether the dc link voltage is stable is determined according to whether the dc link voltage varies within a critical range.
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Families Citing this family (2)

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Publication number Priority date Publication date Assignee Title
DE102019129348A1 (en) * 2019-10-30 2021-05-06 Friedrich-Alexander-Universität Erlangen-Nürnberg System for the treatment of water and procedures for it
CN117365973B (en) * 2023-12-07 2024-02-09 四川省农业机械科学研究院 Solar water lifting method and system for weak light and weak signal area

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101355319A (en) * 2008-09-17 2009-01-28 南京航空航天大学 Method for improving operation reliability of current-control type inverter output short circuit
CN103940045A (en) * 2014-04-22 2014-07-23 广东美的集团芜湖制冷设备有限公司 Solar air conditioner and control method and device thereof
CN105186907A (en) * 2014-06-10 2015-12-23 Ls产电株式会社 Method for voltage dip compensation of inverter
ES2607253A1 (en) * 2017-01-19 2017-03-29 Universidad Politécnica de Madrid Procedure and control device for photovoltaic pumping systems (Machine-translation by Google Translate, not legally binding)
CN107370187A (en) * 2017-09-08 2017-11-21 中南大学 A kind of photovoltaic microgrid system and photovoltaic microgrid system control method

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2176667B (en) * 1985-06-11 1989-07-05 Toshiba Kk Electric motor running system employing a photovoltaic array
JPH0895655A (en) * 1991-04-26 1996-04-12 Tonen Corp Inverter control system for drive of solar battery
JP3027891B2 (en) * 1993-02-02 2000-04-04 富士電機株式会社 Control method of variable speed inverter
JP2000060179A (en) * 1998-08-04 2000-02-25 Fuji Electric Co Ltd Method for controlling solar light inverter for driving pump
US6229278B1 (en) * 1999-09-29 2001-05-08 Rockwell Technologies, Llc Voltage and current limiting method and apparatus for a voltage/frequency drive
TW201223111A (en) * 2010-03-15 2012-06-01 Solar Semiconductor Inc Systems and methods for operating a solar direct pump
US9042141B2 (en) * 2013-02-07 2015-05-26 Caterpillar Inc. Control of energy storage system inverter system in a microgrid application
JP5731574B2 (en) * 2013-05-27 2015-06-10 シャープ株式会社 Inverter control device
KR101830666B1 (en) * 2013-09-17 2018-02-21 엘에스산전 주식회사 Power conversion apparatus
JP6546203B2 (en) * 2015-02-10 2019-07-17 株式会社東芝 CONTROL DEVICE FOR POWER CONVERTER, CONTROL PROGRAM, AND POWER CONVERTER
KR102028328B1 (en) * 2015-04-14 2019-10-04 엘에스산전 주식회사 Apparatus for controlling grid-connected inverter
KR101783121B1 (en) * 2016-01-18 2017-09-28 엘에스산전 주식회사 Inverter

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101355319A (en) * 2008-09-17 2009-01-28 南京航空航天大学 Method for improving operation reliability of current-control type inverter output short circuit
CN103940045A (en) * 2014-04-22 2014-07-23 广东美的集团芜湖制冷设备有限公司 Solar air conditioner and control method and device thereof
CN105186907A (en) * 2014-06-10 2015-12-23 Ls产电株式会社 Method for voltage dip compensation of inverter
ES2607253A1 (en) * 2017-01-19 2017-03-29 Universidad Politécnica de Madrid Procedure and control device for photovoltaic pumping systems (Machine-translation by Google Translate, not legally binding)
CN107370187A (en) * 2017-09-08 2017-11-21 中南大学 A kind of photovoltaic microgrid system and photovoltaic microgrid system control method

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